35 resultados para Lady Franklin Bay Expedition (1881-1884)


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An exceptional specimen of the Late Ordovician mollusc ‘Helminthochiton’ thraivensis Reed, from the Katian of the Lady Burn Starfish Beds, southwest Scotland, preserves gut contents that include nine pelmatozoan ossicles. These are interpreted as including two nodal and five intermodal columnals, and two radice ossicles from the attachment structure. The stem was cyclocyclic and heteromorphic, possibly N212. Radice ossicles were wider than the height of nodals, so radice scars must have encroached onto the latera of adjacent pluricolumnals. These features were compared with the 26 known pelmatozoan taxa from the Lady Burn Starfish Beds. Paracrinoids (one species) and glyptocystitid rhombiferans (six species) were discounted as prey because of their cemented attachment, and incorrect columnal morphology and lack of attachment, respectively. Of 19 species of crinoids, eight are discounted in which the column is pentagonal, tetragonal or unknown. Of the remaining eleven species, only the monobathrid camerate Macrostylocrinus cirrifer Ramsbottom satisfies all criteria for identification of the prey, including heteromorphy and radice scars encroaching adjacent internodals.

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The gametogenic and spat settlement patterns of two Mytihis edulis beds were studied in Dundrum Inner Bay, Northern Ireland. There was evidence of gonad development throughout the year with the main development period between November and March. Spawning was protracted, lasting from May to November. Slight inter-annual and inter-population differences in the riming of the phases were observed but the cycles at both beds were broadly similar to each other and to those of other British and Irish sites. Settlement occurred throughout the year and there was evidence of both primary and secondary spat settlement at both sites. Although the reproductive cycles were similar, distinct seasonal and inter-site differences in spatfall were apparent. At the Downshire Bridge bed, settlement peaked during summer and was dominated by spat in the 0•;5-1•0 mm size range. At Ballykinler, settlement levels were highest in the winter months and larger (>1 mm) spat dominated the samples. The orientation of spat collection pads also significantly affected numbers of the larger (>1 mm) spat. Collectors facing the flood tide attracted significantly more secondary settlers than ebb-facing collectors. This effect varied seasonally and was greater at the Ballykinler bed. It is suggested that hydrodynamic regimes may be an important factor in the differences in settlement patterns of M. edulis.

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[Reviews]

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Concrete structures in marine environments are subjected to cyclic wetting and drying, corrosion of reinforcement due to chloride ingress and biological deterioration. In order to assess the quality of concrete and predict the corrosion activity of reinforcing steel in concrete in this environment, it is essential to monitor the concrete continuously right from the construction phase to the end of service life of the structure. In this paper a novel combination of sensor techniques which are integrated in a sensor probe is used to monitor the quality of cover concrete and corrosion of the reinforcement. The integrated sensor probe was embedded in different concrete samples exposed to an aggressive marine environment at the Hangzhou Bay Bridge in China. The sensor probes were connected to a monitoring station, which enabled the access and control of the data remotely from Belfast, UK. The initial data obtained from the monitoring station reflected the early age properties of the concretes and distinct variations in these properties were observed with different concrete types.

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This paper discusses the importance of integrated sensing systems comprising techniques that give different types of data from a structure exposed to the marine environment so that its service life could reliably be predicted. For this purpose, a novel sensor combination was designed and installed in concrete panels which were exposed to Hangzhou Bay Bridge in China. The integrated sensor probe was used to monitor the cover concrete as well as the reinforcement. The sensor probes were connected to a monitoring station, which enabled access and control of the data remotely from Belfast, UK. The initial data obtained from the monitoring station gives interesting information on the early age properties of concrete and distinct variations in these properties with different types of concrete. This paper also reports the variation in electrical properties of different concrete samples and environmental data in response to the marine exposure condition at Hangzhou bay bridge.

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Malone, C.A.T. and S.K.F. Stoddart, in 1979. Cambridge University.